International Publication No. WO 2011/148753 (hereinafter referred to as “WO 2011/148753 A1”) discloses an arrangement for controlling a pressing force (reaction force) on an accelerator pedal 32 in a hybrid vehicle.
According to WO 2011/148753 A1, an accelerator opening threshold value is set to a greater one of the values of a first accelerator opening and a second accelerator opening for each of respective vehicle speeds ([0036]). The accelerator opening threshold value is a threshold value for increasing a pressing force on the accelerator pedal 32, so that the pressing force is greater than a base pressing force ([0033]). The first accelerator opening is an accelerator opening defined by subtracting a predetermined accelerator opening quantity α from an accelerator opening on an engine startup line, which serves as a threshold value for switching from an EV travel mode to an HEV travel mode ([0035]). The EV travel mode is a travel mode in which the vehicle travels on only the power of a motor generator 2. The HEV travel mode is a travel mode in which the vehicle travels on the power of an engine 1 in addition to the power of the motor generator 2 ([0014]). The second accelerator opening is an accelerator opening defined by adding an accelerator opening quantity β, which acts to achieve a drive power that accelerates the vehicle at a constant rate, to an accelerator opening that serves to make the vehicle cruise at a constant speed on a flat road for each of the respective vehicle speeds ([0035], [0038]).
Japanese Laid-Open Patent Publication No. 2005-271618 (hereinafter referred to as “JP 2005-271618 A”) discloses an accelerator-reaction-force control apparatus for use on a hybrid electric vehicle. According to JP 2005-271618 A, more specifically, the vehicle has a motor-driven domain in which the vehicle is driven by a vehicle driving motor 7, and an engine-driven domain in which the vehicle is driven by an engine 6. When the motor-driven domain switches to the engine-driven domain, the reaction force applied to an accelerator pedal 2 increases when the accelerator pedal 2 is pressed (Abstract). Therefore, switching of the drive source from the motor 7 to the engine 6 is indicated to the driver by means of the reaction force that is applied to the accelerator pedal ([0005]).
Furthermore, JP 2005-271618 A discloses a control process for driving the vehicle with only the engine 6 and charging the battery if the amount of electric energy charged in the battery is not equal to or greater than a predetermined value (in FIG. 4, S1: NO→S9, [0018], claim 2).